Symptomatology.—­On visual examination of the subject at rest, one may note the hypertrophied condition of the affected tendons.  Their transverse diameter is usually perceptibly increased and in many cases, there is an increase in the antero-posterior diameter.  The latter condition causes a bulging of the tendon that is so noticeable, because of the convexity thus formed, it is commonly known as “bowed tendon.”

[Illustration:  Fig. 20—­Contraction of the superficial digital flexor tendon (perforatus) of the right hind leg, due to tendinitis.]

In chronic tendinitis there occurs repeated attacks of inflammation wherein lameness is pronounced and there exists in reality, at such times, acute inflammation of a hypertrophic structure, where at no time does inflammation completely subside.  Therefore, in chronic tendinitis there is to be found at times the same conditions which characterize acute inflammation, except that there is usually a variance of symptoms because of the difference in the degree of inflammation and pain.

The diagnosis of contraction of tendons is an easy matter because of the fact that relations between the phalanges are constantly changed with tendinous contraction.  If one bears in mind the attachments and function of the digital flexors, no difficulty is encountered in recognizing contraction of either tendon.

Contraction of the superficial digital flexor (perforatus), when uncomplicated, is characterized by volar flexion of the pastern joint.  The foot is flat on the ground and the heel is not raised because the superficial flexor tendon does not have its insertion to the distal phalanx (os pedis) and therefore can not affect the position of the foot.

By causing the subject to stand on the affected member, one may outline the course of the flexor tendons by palpation, and in this way recognize any lack of tenseness or contraction of tendons or of the suspensory ligament.

[Illustration:  Fig. 21—­Contraction of the deep flexor tendon (perforans) of the right hind leg, due to tendinitis.]

Contraction of the suspensory ligament would cause the pastern joint to assume the same position as is occasioned by contraction of the superficial digital flexor (perforatus) tendon, but when the subject is bearing weight on the affected member, it is easy to determine that no contraction of the suspensory ligament exists, by noting an absence of abnormal tenseness of this structure.  And finally, contraction of the suspensory ligament is of rare occurrence.

Contraction of the deep flexor tendon (perforans) causes an elevation of the heel.  The foot can not set flat because the insertion of the deep flexor tendon to the solar surface of the distal phalanx (os pedis) causes when the tendon is contracted—­a rotation of the distal phalanx on its transverse axis—­hence the raised heel.  No other tendon has this same effect on the distal phalanx and the condition is correctly diagnosed without difficulty.